I personally think of the water as space, rather than spacetime. I think time is a byproduct of space-mass interactions. I could of course be very wrong!
Space in [x,y,z], spacetime is [x,y,z;t]. It's math. Space represents the physical object, which is currently named as "physical vacuum" (literally "physical emptiness", where "physical" means that emptiness is not empty). It's hard to say what is represented by spacetime in math models.
I personally think of the water as space, rather than spacetime. I think time is a byproduct of space-mass interactions. I could of course be very wrong!